1. Field of the Invention
The present invention relates to pigments and chemical groups attached onto pigments. More particularly, the present invention relates to improved methods for attaching a variety of different types of chemical groups, such as polymers, onto pigments.
2. Description of Related Art
Methods exist for the grafting of polymers to the surface of carbon black which contain specific surface groups (e.g., phenols and carboxyl groups), such as with channel blacks. However, these methods are not easily applied to the surface grafting of polymers onto furnace and acetylene blacks, because these carbon blacks generally lack these specific functional groups. The methods described herein have the advantage that allows for the surface grafting of polymers to the surface of carbon black, regardless of the inherent functional groups.
Pigments having polymers grafted to their surface have been found to provide improved performance when used in an inkjet ink. These materials afford printed images which are notably more waterfast, highlighter smearfast, and smudge resistant than conventional inks. The printed images also show improved edge acuity and intercolorbleed properties. The dispersion stability is also greatly improved.
U.S. Pat. No. 5,851,280 discloses methods for the attachment of organic groups onto pigments, including via a diazonium reaction wherein the organic group is part of the diazonium salt. Through reaction with a pigment, like carbon black, the organic group attaches onto the pigment. These modified pigments can be used in a variety of applications, such as inks, inkjet inks, coatings, toners, plastics, rubbers, and the like.
There is a desire by those in the industry to further develop methods of attaching organic groups, and primarily polymers, onto pigments for the same and similar applications described above. These additional methods may provide advantageous alternatives to forming modified pigments.